Self-organized C70/C60 heterojunction nanowire arrays on Si(1 1 0) for Si-based molecular negative differential resistance nanodevices

Abstract

Periodic organic heterojunction nanowires on Si(110) were successfully constructed through the self-organization of C70 molecules on the nanotemplate of parallel C60-triplet nanowire array on Si(110) at room temperature. Scanning tunneling microscopy images show that the preferential adsorption of three C70 molecules (i.e., C70 triplet) at the bridge site of two C60 triplets makes C70-triplet nanowires grow epitaxially along original C60-triplet nanowires, leading to the formation of parallel-aligned C70-triplet/C60-triplet heterojunction nanowires over a large area on Si(110). Scanning tunneling spectroscopy results show that these C70/C60 heterojunction nanowires on Si(110) exhibit obvious negative differential resistance (NDR) at room temperature. Using first-principles calculations based on density functional theory and non-equilibrium Green’s function formalism, we suggest that the origin of observed NDR of C70/C60 heterojunction nanowires on Si(110) is mainly attributed to the relatively weak interaction between C70 molecules and Si(110) via the spacers of C60 molecules. This controlled organization of mesoscopically-ordered organic heterojunction nanowire array on Si(110) provides a feasible way for molecular engineering of one-dimensional functional Si-based molecular hierarchical nanoarchitectures by deposition of tailored molecules on parallel C60 molecular nanowire arrays on Si(110), realizing the large-scale integration of desired molecular functionalities into Si-based organic nanodevices for applications in nanoelectronics, photovoltaics, and spintronics.